npm config map is not being set properly

[BigAB]

How often can you reproduce it?

• Always
• Sometimes
• Rarely
• Unable
• I didn’t try

Description:
Steal config map does not seem to be being set properly.

Steps to reproduce:

1. Include a link to your project (if possible)

Here is a gist you can clone to show the issue.
https://gist.github.com/BigAB/ae311de12272af411969f477e6f8c1a5

preact-compat should be a drop in replacement for react and react-dom and so map should swap them out fine. But in the gist, if you serve it you can see steal is still trying to import react.

The relevant part of the gist is mostly this in `package.json:

  "steal": {
    "map": {
      "react": "preact-compat",
      "react-dom": "preact-compat"
    }
  }

2. Detail the exact steps taken to produce the problem

Clone the gist. Run npm install. Serve the root. See in the console that react is trying to load and System.map only has @loader/@laoder and @steal/@steal keys.

3. Include a gif if applicable

Expected results:

I expect everything to work, for every call to import React from 'react would return the preact-compat module instead

Actual results:
Steal fails to load react because it isn't there, and the config in npm does not even appear to be merged into System.map

Environment:

Software	Version
Steal version	1.5.2
Steal-tools version	1.3.5
node -v	v8.0.0
npm -v	5.0.2
Browser	Chrome 58.0.3029.110
Operating system	macOS Sierra 10.12.5

[matthewp]

This is caused by progressive fetching of package.jsons. The problem is that the left-hand side is not an npm module, so the code that is supposed to load preact-compat is never triggered. I suppose the fix is that we should fetch the right-hand side packages right away and not wait, if the left-hand side isn't npm. Going to look into what this would take to fix.

[matthewp]

Blocked by #1210

[matthewp]

Breaking test added in ff9c28d